Example III: Synthesis of 3-chloro-2-fluoro-5-(trifluoromethyl)benzonitrile
Thionyl chloride (6.0 g, 50 mmol) was slowly added to a slurry containing 3-chloro-2-fluoro-5-(trifluoromethyl)benzamide (4.0 g, 16 mmol) and 15 mL of dimethylformamide at 0 °C with continuous stirring. The reaction mixture was continued to be stirred at 0 °C for 1 hour. Subsequently, the reaction mixture was diluted with 25 mL of pentane and neutralized by adding saturated potassium carbonate solution dropwise. After completion of neutralization, the reaction mixture was filtered to remove insoluble impurities. The pentane solution was dried with anhydrous sodium sulfate and the solvent was subsequently removed by distillation under reduced pressure to afford the target product 3-chloro-2-fluoro-5-(trifluoromethyl)benzonitrile in 71% yield with a boiling point of 75-85 °C/20 mmHg.
